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Athena landed in a dark crater where the temperature was -280° F / -173° C
by 01-_-
Here's the hole it fell into:
Great shoutout to Arizona State University for the images. I like to see when someone or some group gets some recognition for work they have performed in relative obscurity for a very long time. Years of craft, getting better and better at something most don't bother with. Then suddenly your expertise gets a spotlight in a meaningful way.
(Yes, I suppose there are many other sources that could provide images. These happen to be from ASU.)
There's a mote on the crack on the Mössbauer spectrometer on the instrument arm on the rover in the hole in the bottom of the sea of tranquility
Related. Others?
Athena spacecraft declared dead after toppling over on moon - https://news.ycombinator.com/item?id=43292471 - March 2025 (340 comments)
The Moon Lander Athena's Fate on the Lunar Surface Is Uncertain - https://news.ycombinator.com/item?id=43283136 - March 2025 (1 comment)
Welp, I worked on this one. Specifically, I worked on the laser rangefinders which are under so much scrutiny. I no longer work at Intuitive Machines, but I'm certainly interested in finding out what happened to the lasers this time.
Ooo. Not sure if you can tell us anything. If you can’t I totally understand.
But in case you can: Was a radar based altimeter considered?
How do you guys deal with kicked up regolith? (I have seen first hand how hard heavy snow is on lidars, and would imagine that regolith “shower” is similar, but what do I know.)
The lasers are smaller and lighter than most radar systems. They're also pointed out at about 45 degrees from the lander and they're not supposed to be used for the last few dozen meters of descent.
Thank you!
some of the comments here are suggesting the lander chose that spot, as opposed to crashing and skidding across the surface before settling in the spot purely due to inertia, what's the merit to that?
I did not work on the HDA algorithm which is responsible for landing site deviation, but this technology was inherited from NASA's Project Morpheus, which could intelligently detect hazards and divert to safer sites.
Still unclear what happened. Did they not anticipate a big moon hole or did navigation fail when the rangefinder failed?
Scott Manley has a great video explaining what he thinks happened. https://youtu.be/ISZTTEtHcTg?si=0LZFyiCysBiFZrMz
Scott Manley and I agree that altitude signal shouldn't matter if navigation is correct. Athena simply risked touchdown, and it didn't find a flat spot, it found a hole.
Can you quote the bit you think is relevant here?
He's saying modern spacecraft can null out the horizontal velocity to land, but without an altimeter, you don't necessarily know when to do so, nor when to give the thrusters a little boost to avoid an obstacle you're about to hit, like a plateau.
Does anyone know an extension that strips this tracking information and normalizes YouTube URLs?
There's tons... Firefox: https://addons.mozilla.org/en-US/firefox/addon/clearurls/ Android: https://github.com/svenjacobs/leon
Just in case, I’m using my own violentmonkey scripts rather than hoping for extensions, and everyone can do that too (now only on firefox, I guess, and maybe brave).
For example, I remove &t=<n> from urls that youtube added recently in addition to regular watch position restoration. This broke it for me and they don’t seem to plan a revert.
That is also used if you want to share a video at a particular timestamp with someone. E.g. check this out it happens 40s in. YouTube.com....&t=40s
A little downside, yeah, but these scripts can be easily toggled. What can't be easily done is finding my last timestamp in a 5h long vod when &t-in-history screws it up.
tldw: speculation: landed with too much lateral velocity and one of legs broke
I'm not sure what you find unclear. Navigation was fine - "Athena knew where it was relative to the surface of the Moon" - but without a working altimeter it was kinda fucked for actually touching down.
Hard landing, skid, tip.
> "Athena knew where it was relative to the surface of the Moon" - but without a working altimeter it was kinda fucked for actually touching down.
Z is an axis that exists in our 3d world, and a required value for any relative position, which means it DID NOT know where it was, relative to the moon.
Ya the wording was not quite … satisfactory. I think they meant , it could tell X and Y, but not Z.
But all three are important.
Related - I’m not clear how the article can describe that landing as “not crashing”. If that was not a crash, what was it? Will they call it a crash only if there are Hollywood-style explosions?
Bringing "Hollywood-style explosions" into it is a little much. If you slam the breaks on in your car, your tires hit some debris in the road, and you spin around and end up somewhere you didn't intend to be, but the car wasn't meaningfully damaged (i.e. you didn't hit other cars or manmade structures), you made a dangerous uncontrolled maneuver, but you didn't crash. That seems more like how they're describing this "skid."
Relevantly, it sounds like this lunar spacecraft was still functioning after the hard (non-)landing. The only reason it died after that was because of debris settling on the solar panels, which made it run out of power.
If you do something with your car that ends up with it skidding on its side, that's a crash by any possible definition.
Probably, but this is a space probe, not a car. It's lighter than a car, and is operating in an environment with less gravity.
One of the legs broke off which requires significant forces not just a skid.
I mean if my car lands on the side and one of it’s wheels fell off that’s a significant crash.
The leg breaking off is probably the best supporting evidence towards calling it a crash, I'll agree with that.
"The only reason?" One reason for prematurely losing most of the investment is enough. The car analogy is inadequate but let's say my car skids gently into a position from which it won't start and I can't get out and I slowly die of starvation and/or hypothermia. Am I glad that I didn't "crash?"
I didn't say the mission was a success. I was addressing someone's nitpick over the definition of the word "crash."
If the space probe had a wiring failure after landing that caused the loss of "investment," that wouldn't be a crash. It would be a separate problem.
But if they knew where it was relative to the surface of the Moon, they could have subtracted that from where it wasn't, or where it wasn't from where it was (whichever is greater), to obtain a difference, or deviation. The guidance subsystem could then use deviations to generate corrective commands to drive the missile from a position where it was to a position where it wasn't.
The top-heavy design didn't help things either. I'll be shocked if they don't go three-for-three on landing sideways given IM3 has the same tall design.
The company claims it's not as top-heavy as you'd think from pics:
https://www.theregister.com/2025/03/07/intuitive_machines_la...
> At his press conference earlier today, Altemus defended the design, saying the spacecraft doesn’t have a high center of gravity because most of its cargo attaches to the base of the vehicle. He said there were no plans for a radical rethink of his company's design.
(We see this in returning F9 first stages, as well.)
>> The top-heavy design didn't help things either
Just wait for SpaceX to start trying to land starships on the moon. Also vertically. Also doomed to tip over whenever the surface is slightly out of spec.
Why does this even have to be a problem?
We can send small probes to image the moon in incredibly high resolution. It's a big place I'm sure there is a perfectly flat rock somewhere they can use.
Have you ever seen a perfectly flat rock anywhere on earth? One capable of supporting a large rocket? Also, the moon doesn't have the various navigation systems (GPS/radar) that is used when bringing rocket stages back the pad.
> Just wait for SpaceX to start trying to land starships on the moon. Also vertically
SpaceX has done it. To date, other nation-states have tried and failed to replicate their achievements in this domain.
IM’s design is wrongly optimised and probably requires a rethink. That the CEO won’t contemplate this isn’t a great sign for the company.
SpaceX has done it.
SpaceX has landed Starship on the moon?!
SpaceX has repeatedly and reliably landed vertical stacks. On any body. Out of the engineering problems inherent to HLS, sticking the landing isn’t material because for them, for that team, it isn't as novel a problem as e.g. in-orbit refuelling or getting Raptors to relight on the Moon.
Put another way, just because SpaceX has done it doesn't mean the same problem carries the same risk for a team like IM's.
Has SpaceX ever landed their rocket on a surface that isn't purposefully engineered to be flat?
Multiple sea landings, but I guess you'd argue those don't count since the vehicles tip over in water and explode.
Moving barges in the sea should qualify though.
A moving barge with a known flat surface of a known hardness and stability is a whole different category of difficult than doing the same thing on naturally occurring terrain with unknown voids, hardness, roughness and consistency.
Is a landing barge not "purposefully engineered to be flat"?
So what you're saying is we need to blast some barges into space and land them on the moon so we have a flat surface for starship to land on?
They also have the atmosphere, with drag that will make all velocities trend towards zero. Don’t have that on the moon, gotta do it all with fuel. More than half of the energy she’s by the returning falcon is aerobraking.
Yes, the moon has substantially less gravity but it’s also exponentially harder to get the fuel there.
"the atmosphere, with drag that will make all velocities trend towards zero"
Did you forget about gravity? Terminal velocity in free-fall is not zero!
Trend towards. The rocket is descending far faster than low altitude terminal velocity.
Lol. SpaceX has landed on prepared surfaces, concrete pads on land or on large barges. They literally have a big X to mark the target. Let's see them land on some random beach, an uneven surface that may or may not subside. But that is still peanuts comparted to the moon's surface.
> that is still peanuts comparted to the moon's surface
Sure. I'm not trivialising the problem in an absolute sense. Just going from floating barge or chopsticks to Moon is a simpler set of problems than reïnventing the sort of translational velocity and attitude control needed to get to first base.
For selecting and touching down on an unprepared surface, rockets are not the stepping stone. Start with helicopters. It is the same problem: can I land there and what will happen when I put weight on the surface. Try programing a large helicopter to identify and land on a random chunk of rocky terrain. It is not easy. And the bigger/taller the craft, the more difficult it becomes. Then add a 10-second time limit.
Are the sky cranes of Mars viable without an atmosphere?
You say this based on your history of landing rockets on the moon?
And on your history of dealing with the lunar regolith near the poles?
> You say this based on your history of landing rockets on the moon?
Actually, mini propulsive landers in lunar regolith stimulant. Yes. In atmosphere and with Earth gravity, both of which make it more annoying and more difficult.
For any of these landings, it's a problem of 3d positional/velocity precision. SpaceX has prove that they can reliably land on a target, usually within meters, with negligibly delta velocity on contact.
In other words, they've proven they have the control systems in place for placing a craft at a precise location, with a precise velocity. What requirement do you see outside of this that are far outside of placement and velocity? Autonomous mapping and adjustments for approach maybe?
Let's not assume they're going to try to use their current earthly landing legs.
> land on some random beach,
They did this I believe two starships ago, when they landed in the ocean. Came to zero xyz velocity some target distance above the water, and hovered for a bit. Unfortunately, the surface tension of the sea couldn't support the weight once they lowered for touchdown.
> 3d positional/velocity precision. SpaceX has prove that they can reliably land on a target, usually within meters
On Earth, which has GPS. On a very highly engineered landing surface.
Landing on inertial guidance on soft regolith is a whole different ballgame.
> Landing on inertial guidance
Which is not the future. Optical/lidar/positioning radio is the future, to make it closed loop (NASA’s Laser Retroreflector Array for high, lidar/optical for low altitudes).
> On a very highly engineered landing surface.
As I mentioned, we shouldn't assume the earthy landing legs are used. That would be a very silly assumption.
From what I can extract from your comment, you believe that the positioning system and landing legs are the issue, rather than the control systems. I suspect both are somewhat related: positioning system to place it over predictable regolith with some, yet-undeveloped, landing legs that need to work at 1/6th gravity.
I'm of the opinion that it's possible/solvable, as is NASA. It would be helpful if you would answer why you think it's not possible: what requirement do you see that make positioning and landing on regolith unachievable for SpaceX?
[1] https://www.nasa.gov/centers-and-facilities/langley/nasas-la...
It may be possible. It may also be that the regolith is too fluffy in that area to support such a large structure without a pad. I don't believe we know.
Athena had multiple laser altimeters on board: they failed to get a fix, perhaps because of the weird surface.
It's my opinion that this isn't something that's easy to do, even for a company that has landed on Earth.
Keep that Musk copium going, man!
Why do people keep thinking this thing is top heavy just because its taller than wide?
The heavy bits are at the bottom.
> Why do people keep thinking this thing is top heavy just because its taller than wide?
Because it keeps falling over?
The landing leg broke. How does that show you its top heavy?
I didn't say it was top-heavy. I answered the question, "Why does everyone think it is top heavy?"
Ah complete total ignorance. Figures
Because itbit wasn't top-heavy, a broken landing leg would just leave it slumped at an angle. Not fallen-over.
Consider the difference between removing the leg of a chair versus a stool.
i think this becomes somewhat less of an issue once SpaceX gets Starship fulfilling contracts at scale. they're limited in width by the max payload faring width for Falcon 9, which is like half that of starship. add to that an exec claimed it's tall but not necessarily top-heavy as mass isn't evenly distributed throughout.
Or use New Glenn which works now and has a larger faring.
Was there no functioning laser or radar altimeter for the final descent phase?
"However, the lander's altimeter had failed."
Looking at this closely, it was working, however it was noisy. I speculate that they didn't correctly anticipate the moon dust problem. Laser rangefinders may not be a workable solution for future landings.
So engineers at Intuitive Machines had checked, and re-checked, the laser-based altimeters on Athena. When the lander got down within about 30 km of the lunar surface, they tested the rangefinders again. Worryingly, there was some noise in the readings as the laser bounced off the Moon. However, the engineers had reason to believe that, maybe, the readings would improve as the spacecraft got nearer to the surface.
Noise at 30km altitude probably points more towards a sensor issue than dust.
May it be that laser bounced off exhaust plume?
Unless their processing is very weird, that shouldn’t be the issue.
You send a pulse and record the output of a detector to listen for the reflection. If the laser is reflected at the plume, you should get some pulses very quickly, but also faint and spread out in time, which you would be able to tune out. And the real response from the ground should be more narrow because it’s reflecting at a single distance.
If very short range noise influences the signal when measuring 30km real distance, you’re doing something wrong.
Laser is angled outwards at approx 45 degrees, I think it's well away from the exhaust plume.
I think it would be unlikely that a plume was caused from 30km away on something with no atmosphere.
LRFs and radars on the Moon has been fine for a long time, it can also be angled away from gravity axis and multiplied by sine theta if needed.
If navigation was fine, why was touchdown on a plateau?
Because "where am I" and "how high am I over that position" are very different things.
Visual demonstration of being at the wrong altitude in the right spot: https://www.f-16.net/f-16-news-article968.html
If you don’t know your altitude, navigation isn’t fine though. Navigation should give you a position in all axes.
Comment was deleted :(
It touched down with a large horizontal velocity component
That’s another thing that bothered me about this story. They said they knew where the craft was , relative to the surface of the moon. Wouldn’t that also mean they should know of any substantial horizontal (x/y) component of velocity?
I don't know if it's the case, but there's a difference between knowing something and calculating its derivative fast enough for it to be useful.
Yes, through image analysis.
> As a result, the privately built spacecraft struck the lunar surface on a plateau, toppled over, and began to skid across the surface. As it did so, the lander rotated at least once or twice before coming to a stop in a small, shadowed crater.
Oh yeah, we've all Kerbaled it in like that at one point or another.
If you take the time to study the documentation from the 1950s & 1960s, the engineering culture of that era appears to be markedly different from the engineering culture prevalent today. And I think it's deeply rooted in the symbiotic relationship between computing, Baumol's cost disease and our obsession with precision, results-oriented, MBA-style-min-maxing, "good enough for government work" engineering.
Robert Truax, the designer of the Sea Dragon, loved to promote the design paradigm of Big Dumb Boosters. Instead of many small, sophisticated rocket engines, what if we made one big robust one that can take a lickin' and keep on kickin'.
The idea was to relax the mass margins and to create big. dumb. boosters. It's the approach TRW explicitly followed for the Lunar Module engine,
> "There was an amusing but instructive side to this program. TRW farmed-out the fabrication of the engine and its supporting structure, less the injector that they fabricated themselves, to a "job-shop" commercial steel fabricator located near their facility . The contract price was $ 8000. Two TRW executives visited the facility to observe the fabrication process. They found only one individual working on the hardware, and when queried, he did not know nor care that he was building an aerospace rocket engine."
> " I had arrived late to witness the test, and only saw the firing. I was told by others who witnessed the entire test procedure that the engine was pulled out of outdoor storage where it lay unprotected against the elements. Before it was placed on the launch stand, the test crew dusted off the desert sand that had clung to it. This unplanned inlcusion [sic] of a bit of an environmental test also demonstrated hardware ruggedness of the kind no other liquid rocket eingine [sic] could approach."
These programs had a lot of capital behind them. Some components required precision engineering, but there's a very clear through line and embrace of the "we gotta make stuff that can take a lickin' & keeps kickin'" philosophy.
Modern engineering approaches seem to be the opposite of that. I think we've become so accustomed to living in a silicon driven world where our personal devices are engineered at microscopic level that we've forgotten how to do things the Apollo-era way.
For example, to the best of my knowledge, IM-2 doesn't use RADAR — they're using LIDAR and optical navigation instead. Perhaps it is to save on mass and power so that more payload reaches the surface. Perhaps optical navigation was declared to be "good enough." Perhaps it doesn't make sense from a minmaxing of capital perspective. But this philosophy may not be suited to an untamed frontier.
China adopted the Surveyor / Apollo-era philosophy. Their first successful lander, Chang'e 3, used the same hover & fall technique as Surveyor.
> The vehicle will hover at this altitude, moving horizontally under its own guidance to avoid obstacles, and then slowly descend to 4 m above the ground, at which point its engine will shut down for a free-fall onto the lunar surface. The landing site will be at Sinus Iridum, at a latitude of 44º.
The follow up missions up-ed the ante every time, but they seem to have consistently focused on the robustness of their craft over precision, MBA-spreadsheet-oriented minmax-ing.
> "I think we've become so accustomed to living in a silicon driven world where our personal devices are engineered at microscopic level that we've forgotten how to do things the Apollo-era way."
This is a really interesting point. I think a practical issue in modern times as well is that companies are being inspired by SpaceX while forgetting that it took SpaceX alot of work to get to the point of being able to do things like casually land a 20 story tower in the middle of the ocean on a barge, let alone the even more ridiculous 'stunts' they're doing with Starship.
Apollo was starting from the perspective of trying to do something where it was even debatable about whether it was possible. And so I think there was a lot more 'humility' in design, for lack of a better word.
As they say, when in doubt, take a bigger hammer. Not a sophisticated high-precision low-tolerance tool. That tool works well (better than the hammer) when you already have no doubts, when you precisely understand how things are going to work.
You're criticizing the prioritization of cost, not the concept of trying to solve for constraints. Engineering is about constrained optimization to meet customer needs.[1] Learning this is a core part of the curriculum at my accredited engineering school.
> Engineering design is a process of making informed decisions to creatively devise products, systems, components, or processes to meet specified goals based on engineering analysis and judgement. The process is often characterized as complex, open-ended, iterative, and multidisciplinary. Solutions incorporate natural sciences, mathematics, and engineering science, using systematic and current best practices to satisfy defined objectives within identified requirements, criteria and constraints.
> Constraints to be considered may include (but are not limited to): health and safety, sustainability, environmental, ethical, security, economic, aesthetics and human factors, feasibility and compliance with regulatory aspects, along with universal design issues such as societal, cultural and diversification facets.
It's not an MBA philosophy but is intrinsic to the profession. Apollo didn't go up because of vibes, it went up because engineers knew the goals going in and to figured out how much fuel was needed to go to the moon. It also went up because the United States was willing to spend over a quarter of a trillion dollars (adjusted for inflation) on getting there,[2] and ignored the arguments that it was a giant waste of money while there were social problems at home.[3]
[1]https://egad.engineering.queensu.ca/wp-content/uploads/2023/...
This comment isn't directed at you jjmarr, I appreciate your take, but I think it's important to point out that,
> constrained optimization to meet customer needs
For most of its existence as a formal field, engineering wasn't about making geegaws that "meet customer needs." It was about building stuff that matters. Houses that didn't collapse. Roads and machines that made it possible to traverse vast distances. Toys that delighted us. Aquaducts that delivered clean water. Drainage that helped remove muck. Plumbing that cleaned our cities. Threshers that helped us harvest crops. Lights that vanquished the dark.
The story of engineering is the story of creating technology that helps alleviate want.
You can say that there was a "customer" for each, which is great and all, but that's not why we did it. We did it so that we could move out of the caves and not be in filth and muck all the time.
We did it because it felt good. And we did it because it was the right thing to do.
I don't understand what you are objecting to. Is it just the phrasing that's bothering you? Because from my point of view, "houses that don't collapse" and "machines that can travel vast distances" are all formulations of customer needs. And dealing with contraints is pretty much engineering 101, every project is at the very least constrained on two of these axes: cost, construction time or material availability.
Not GP, but I think the objection is: the engineer wants to build a thing cheaply enough that it functions, and then cheaply as can be while maintaining function.
The MBA wants to build a thing as cheaply as can be while extracting maximum value from the process. Maintaining function is only relevant inasmuch as is necessary for marketing. Enshittification is offensive to the engineer, and is a deliberate calculated tactic for the MBA.
We're replete with case studies, but my favorite is Kitchen-Aid mixers which accumulated a reputation when they were the small version of Hobart mixers, and have in succeeding decades become a cheap pile of crap because the optimization does not care about quality of function so long as the appearance of quality can be maintained. And it's cheaper to look quality than it is to be so.
A close second is Singer in the '70s, which for a while decided to ship items with 100-hour motors because "Folks don't usually spend much time _actually_ sewing". Contrast with the machines built a centuryish before. We've got an early electric model which is still doing fantastic precise work. The engineer would enthuse over the superb work that went into building such a tool, and the MBA would focus on the foregone sales, the value not extracted.
Wait what is even the economic case of landing on the moon? The reason why anyone even does it is either for science or propaganda.
Musk's ranting about colonising space is cute but spaceX is building shit for NASA and the Pentagon.
I was watching this documentary Happy People, about people who live in the Siberian Taiga (by Werner Herzog, would highly recommend). A man is talking about making a new set of skis, and it shows the incredibly long and careful process of selecting the perfect trees, chopping them down in the right way, treating the wood and so on. He mentions how mass manufactured skis are light and cheap and will work fine for a while, but when one breaks and you're in the Siberian wilderness you can't just go to the store for a replacement. That really stuck with me.
1960s US is hardly Siberia and I don't think any NASA engineers had their heads on the chopping block if their designs failed. But engineering philosophy was still rooted in survival; the primary goal was to make something that wouldn't kill you because it fails.
You hear stories about artisans in the old days refusing work because they don't believe what they're being asked to make is safe or reliable enough for the person asking for it. Maybe it's romanticized and idealized, maybe it's just them covering their ass so they don't get blamed. But that philosophy of personal responsibility not just for making things according to the constraints, but for the outcome too, is something that served society well for a long time before slowly disappearing over the past century or so.
It hasn't left without reason. As the things being made became less key to survival and more key to thrival, as the world became more interconnected and safe, it didn't make as much sense. Just think of how many crazy, inventive concepts we use every day wouldn't have been made if they could only be made to work reliably! Our entire modern existence is based off things that don't work reliably. It's a blessing and a curse.
But when we're exploring the final frontier we need frontier thinking and frontier technology; things that, from the ground up, are built to work first with all other constraints secondary. Unfortunately spaceflight endeavors today must invariably build off the 'good enough, when it breaks just make a new one' foundation that permeates modern design at every level. Even if you want to make something nowadays with the sole purpose of working, as long as you're using any technological advancements made in the past 50 years chances are you're using something that wasn't made with that goal in mind.
I think you are presenting a romanticized fictional narrative, especially when it comes to aerospace.
When engineers were working on Apollo and lunar landers, they were working on a set of customer requirements a mile long. Roving tinkerers didn't build the moon rockets. Engineers spent countless hours in design reviews with the customer, in this case, NASA.
Roman engineers didn't build aqueducts and colosseums on a lark, or some sense of poetic destiny.
> stuff that matters
Matters to whom?
Answer: that's the definition of a customer in an engineering project
Matters how / why?
Answer: those are the requirements / user stories.
Helping people by doing engineering feels good and is the right thing to do, but formalizing this process a bit does not detract from it.
The constrained optimization part is good, though.
> If you take the time to study the documentation from the 1950s & 1960s, the engineering culture of that era appears to be markedly different from the engineering culture prevalent today. And I think it's deeply rooted in the symbiotic relationship between computing, Baumol's cost disease and our obsession with precision, results-oriented, MBA-style-min-maxing, "good enough for government work" engineering.
I wonder how much of that is because of public attitudes to government spend. Like if a SpaceX rocket blows up, they're taking innovative, risk-taking approaches to rocket development. If a NASA rocket blows up they're wasting tax payer funding.
Similarly the pressure on NASA to have fewer programs for cost saving is similar. If NASA has two rocket programs, one of which is at a "good enough" level for launching satellites economically into space and one of them is a "safety conscious" rocket for manned launches at a higher per-mission cost, then people look at this and think why is NASA duplicating work and spending. So now they get only one program, so then even launching a GPS satellite is the expensive, human-safe rocket.
> China adopted the Surveyor / Apollo-era philosophy. Their first successful lander, Chang'e 3, used the same hover & fall technique as Surveyor.
Dropping the last 4 metres isn't a sign of having a ruggedized, over-speced "takes a lickin' and keeps on kicking' approach". In lunar gravity, you could drop a raw egg from that height and not perturb the chick inside.
Instead the aim is to avoid throwing up too much moon dust with retro rockets.
Luna 9 (1966) really did need to withstand a bit of a bump, but it was 22km/h, comparable with a fast running pace or a car in first gear, not a high speed impact.
> Dropping the last 4 metres isn't a sign of having a ruggedized, over-speced "takes a lickin' and keeps on kicking' approach". In lunar gravity, you could drop a raw egg from that height and not perturb the chick inside.
Just for maximum pedantry:
Falling 4 m on the moon is like falling 66 cm or about 2 feet on earth. I don’t know about your eggs but the ones I know wouldn’t survive that.
It is all downstream of the loss of the manufacturing industry in America. In the 50s you could entrust a random guy to build a liquid rocket engine in a dusty garage because he spent every day of his career building various pipes and combustion chambers. All of these guys are now dead or retired so when you try to build hardware today you get new grads who settle on LIDAR and computer vision not because it is the best choice but because it is literally all that they are familiar with; the old solutions have all ceased to exist within the minds of employees and classrooms.
This reads like a “comment” version of Destin’s speech to a NASA group a few years ago [0]. The loss of institutional knowledge and fundamentals philosophical differences seem like they’ll need to be overcome.
The talk was to the American Astronautical Society, not specifically a NASA group. But Destin talked as though he imagined everyone in the audience worked at NASA. It actually bothered me a bit - if I had been at that talk I would have been a bit pissed off, because he was basically using it as a channel to talk to people who probably weren't actually even there.
Just youtubers doing youtube things, I guess.
What an absolutely phenomenal speech and video. Just a sort of +1 highly recommended thing. That video was crazy insightful.
Was it? I read it as a pretty hyped up version of "old space guy says to old space people that they're not old spacing enough, presents it as rebellion". In particular (and, to be clear, it's been a while) he kept going "why not do it like apollo" when the entire point is that it isn't Apollo anymore.
Though, again, it's been a while since I watched it.
He wasn't just saying 'do it like Apollo did' in terms of tech, but rather focusing on the process. I think the key takeaway is that one of the main things they did during Apollo was to obsessively try to get everybody to express their honest feedback, and especially negative feedback. Artemis isn't ever going anywhere for a million reasons, of which he listed a couple of random ones, but everybody keeps pretending it is.
That's because the powers that be surround themselves with yes-men or (equivalently) people are afraid of the consequences for stating their honest opinion, when that opinion is negative. It's a problem as old as time. "The Emperor's New Clothes" is based on tales dating back to around 1000AD, and I'm sure it goes back far further than that. This problem destroys competence, destroys countries, and has become ubiquitous in every single aspect of high level public (and to a lesser degree even high level private) decision making in the US.
Notice how things seem to constantly just go wrong in spite of effectively endless resources and manpower? If you look at what we have today in terms of any quantifiable metric we should be able to run circles around the 60s (in terms of, amongst other things, tech advancement) with our eyes shut, yet in practice we're struggling to recreate what they did in the 60s, in 7 years, starting from nothing and on a [relatively] extremely limited budget.
> Perhaps it is to save on mass and power so that more payload reaches the surface.
It doesn't matter how much mass was saved and how much more payload that allowed to reach the surface if the landing isn't successful. Successful landing is mandatory for anything else to matter. The obviousness of this baffles me that it is taken so haphazardly.
I believe that the thing you are missing is Intuitive Machines aims at landing a lot of spacecrafts, not just one. They hope to have a limited number of failures to land which will teach them how to do it reliably. We might doubt will this work or not, but if we accept the plan then it becomes a rational decision to increase the engineering complexity and risks of failure by saving on mass, because in the long run less missions will allow to land more payload.
Though, of course, I wonder how many landings they are planning to do, and how many of them they need to do to compensate for each failure to land.
Again, if you can't stick the landing, you might as well not have any payload on it. So if you're worried about cost, keep testing until you can stick the landing with dummy mass. Once that works, send the real payload. Otherwise, you're just wasting payload.
The mindset difference seems to be that if there's no human on board, so no problemo wasting a lander if something goes wrong. That's just a bad attitude (as well as yaw and roll). If you designed everything with "baby on board" hanging in the window, you'd probably not cut so many corners so sharply. Otherwise, why not just light your cigars with hundred dollar bills. How would you feel if you were on the team building the payload, but the lander guys keep fucking up so you just wasted however much time you spent because "meh, we're just testing". In sports, there's a saying "practice like you play because you play like you practice".
Okay but successfully landing an inanimate carbon rod is easy, but why?
Who said it was easy? I'm saying they are not giving it enough respect because of the attitude of "it's only a test". That's bad. It's still expensive to get to that point. They have become complacent/lazy with the luxury of being able to iterate. Rather than spending money on engineering testing, they just build "real things" that don't work and improve the failed things. Never mind that if procedure 10 failed, you never get to test procedure 11+. So your next launch fails at procedure 11. It's just a bad attitude.
To a point. Landing a solid brick of aluminum isn't much good, unless the entire goal of the exercise is to get a successful landing of something.
>It chose the terminal landing sites with the help of LIDAR and its cameras, but it relied on RADAR and a suite of sensors to have robust navigation.
I think this is the smoking gun. RADAR is usually successful, while LIDAR has a poor record.
If you look at Change 5 and 6, they seem to do the same image processing based landing control. This doesn't seem to be a cost cutting measure, since the image processing is computationally much more complex than using a radar altimeter.
If they can fit 10x the payload for 1/100 the price, then maybe it's okay if some of them fail? Quantity has a quality of it's own.
Dumb question, but why can't it have a few simple telescopic sticks which extend to flip it over if it lands upside down.
Seems it's the second time they fail in this mode.
Definitely not a dumb question. The first lander to land on the Moon (after many failures) is pretty amusing. [1] The Soviets a designed a lander that'd be launched right into the Moon but, just before impact would jettison the lander which itself was a highly reinforced ball that was then designed to simply pound into the Moon at 54kph, but survive the crash. The egg then unfurled and finally humanity had achieved a 'soft' landing on the Moon. Somehow it kind of makes one think of a really elaborate egg drop contest paired with a 'what happens if you jump right before the elevator crashes.'
Like another comment mentioned, complexity and size are big issues. Some more are power/mechanics (fluids, such as for hydraulics, and -280F aren't gonna play well together) and then there's the fact that there's not even a guarantee it'd work. Your legs could get damaged, you might end up in an orientation where none of the legs are appropriate, and so on. So you may be adding a whole bunch of complexity for stuff that might not even save you in the situation it was designed for!
Just give the RCS thrusters enough power to lift it sideways. Works every time in KSP.
Moe parts, more complexity, more weight.
Mass. Each kilogram costs what, millions? Hundreds of millions?
There's a small chance that navigation or landing fails in a way that would make those legs useful, and an even smaller chance that they'll save the mission.
Given tight budgets, this is almost certainly not a gamble worth taking
NASA paid $65M for the launch. It's about 2,000 kilos.
$32k/kilo or so.
battlebots did it first!
Because: 1. It cannot fail in this mode. 2. Testing is done by the user, test results are sent by telemetry and the fix will be done, when the bug can be reproduced on developer's computers.
/s
How about a parachute to keep it the right way up?
Not enough of an atmosphere.
How about a balloon then?
Absent an atmosphere, a balloon is just a heavier parachute.
the altimeter? Surely you would put three on there?
+1
They had the altimeter fail on the previous mission too. Seems like a fairly crucial component of a moon lander.
Armchair rocket scientist here, but if I were on that engineering team I'd lobby hard for less science payloads and more backups for critical instruments for the actual flight of the craft.
The rover and hopper and drill etc all sound cool yes, but worthless if you can't land. Again. For the second time. Because the same critical component failed, again. With apparently no backup, again.
Of course, it sounds so simple. I am sure there is more to it (e.g. perhaps they had backups and everything worked, but they just weren't fit for purpose?)
> They had the altimeter fail on the previous mission too.
Not really. They forgot to toggle the safety switch on before launch, so the laser could not be used:
https://spaceq.ca/simple-error-could-have-resulted-in-intuit...
Had two. One showed so much measurement noise they couldn't trust it, other kept cutting out. Not great.
So three ones, two different models, one in a different location. These are like... basics, no?
If you multiply every critical component by 3x there will be no room left for anything else.
2n + 1 is a basic minimum amount of redundancy for anything critical in a high-value space mission.
This isn't a high-value space mission.
The price of a ride to the moon alone would make this "high-value." Cubesats are an example of when you can get away with no redundancy, but this is not a cubesat.
This is best compared to being a lunar landing cubesat. IM is an order of magnitude cheaper than a comparable NASA lander. Cheap is the point, and cheap carries with it some concessions to risk.
$1M was the amount they spent on the lander. If I recall correctly, they got a ride to the moon for free. Delivering that amount of mass to the moon is worth O($10M). It seems incentives were not properly aligned for this group.
I should also point out that you can fly a scientific mission on a 1U cubesat for ~$100k all in (including launch cost), which puts it in a very different regime.
Getting to the moon is vastly more expensive. 40x is the multiplier that is typically used in the industry. Prior to cancellation, NASA spent $433M on the VIPER lander + rover--NOT inclusive of launch costs.
$1m is crazy cheap.
$1M is not the full price of this mission. $1M is the price of the lander only. They were given a ride on a rocket whose total bill was $62.5 million (just for the launch, but spread among 4 missions).
When you spend $1 million but get $10 million of stuff for free, it's not really a "$1 million project."
The $433M number I quoted was for the hardware only too. Apples to apples.
I worked NASA planetary science before. $1m is CRAZY cheap.
The first moon landing cost $300 billion+ in today's dollars.
Yeah, this is not that, though. We know how to get to the moon, and a small probe is lighter than 3 people plus a vehicle that allows them to make a return trip.
This launch, which had a few other payloads, too, reportedly cost NASA $62 million.
Well the way they did it (twice) means they had space for other stuff, and of course also failed because they didn't have enough redudancy
slippery slope fallacy. just do engineering good
If I’m not mistaken there are three on commercial aircraft.. Seems like the bare minimum for a lunar lander .. I can’t imagine they’re THAT heavy
Heavier than you think, probably. I tried looking up laser altimeters suitable for moon landings and was met with a much higher than anticipated amount of complexity. One thing was clear: the higher the altimeter needs to work, the heavier.
Every gram of weight is directly trading off payload.
Is there any reason why we couldn't have some rudimentary GPS-like satellites around the moon? That could help out these kinds of landers, no?
High lunar orbits is unstable because of Earth influence (i. e. long-term orbiting requires lots of fuel for extensive orbit maintenance). Most low orbits are unstable as well because of uneven mass distribution, but there are some exceptions: https://en.wikipedia.org/wiki/Frozen_orbit Low orbits would also require either more satellites for complete coverage or synchronizing launch window, which is PITA enough as it is now.
But would they need to be in the orbit? Since nothing is on the moon, couldn't you just create a GPS array on the ground?
For a GNSS-type system to work, you need four transmitters in sight. This would imply a moderately dense ground network on the moon for a receiver at orbital height -- and as this article points out, we're not doing great at building even a spare ground network of right-side-up transmitters right now -- but would need increasing density for a descending receiver. We don't really have challenges right now with accurately determining orbital parameters of probes above the moon, it's the final few miles where GNSS-level accuracy would be tempting; but that's also the domain where seeing four ground-based transmitters is basically impossible.
If you were trying to land on a specific site though, couldn't you drop down a dozen or so transmitters at the potential landing site? The assign them a location, and have them transmit the relative location to anything landing near them?
How would you drop them? Don't think a radio transmitter would survive a hard landing, so you will need a proper lander (with altimeter) for each transmitter. And at that point you can just strap your actual payload instead of the transmitter.
The point would be you could drop them a bit randomly, once they land, find out where they are, and tell them where they are, to then talk back to the payload as it's landing.
It's the moon, even a hard landing isn't that hard.
>nothing is on the moon
It's not exactly nothing, the moon itself with its mountains is there and blocking the radio signal and it means propagation isn't unlike that of VHF/UHF on Earth. You still only have no visibility beyond the horizon. In order for it to be visible and useful during landing you would need the base station to be reasonably close. I guess that would make it more akin to ILS/VOR/DME than GPS. That obviously wouldn't be feasible until we have a permanent base there (perhaps an unmanned one).
the moon is made of cheese everyone knows this
Who do you propose should fund lunar GPS for the benefit of private companies who want to land on the moon?
The private companies.
But “who should fund this?” is a separate question from “would this help?”.
I don’t think it would really help that much, and that is the reason why the private companies are not doing it.
Not really, yes (though possibly not for the actual landing, depending on accuracy), and it's actively being worked on: https://www.intuitivemachines.com/post/nasa-awards-intuitive...
IM didn't win the contact because of their landers per se, but obviously as a company they have a vested interest in this kind of lunar infrastructure. Being able to build it with a bunch of public money is a huge win for them
This company's PR team is doing incredible work getting all this type of coverage out of a 0/2 track record with a design everyone else seems to think is obviously flawed.
What’s the prevailing criticism? High COG?
It's tall and narrow and falls over when it hits the ground moving fast. Irritating for intuitive machines whose stance is that mass is not uniformly distributed and center of mass is already low enough to make flight control somewhat challenging.
The criticism should perhaps be that the laser range finders are clearly a liability and a robust/workable backup for telling how far away the ground is needs to be brought along.
hey man we made it on the rock and checked the weather thats cool right
Kinda explain why Neil Armstrong burned up all their fuel except for a few seconds scoping out the landing site in paranoia.
Instead of building all these expensive to launch big landers, why not get some pizza-box sized probes into earth orbit AND THEN do like a slo-mo golf shot arcing to where the moon will be for a super slow/soft landing?
Some will fail but if you launch 100 and get 20-30 working, there you go.
As technology progresses, get it down to a shoe-box sized probe and then in 10 years smartphone sized (in 100 years tic-tac sized).
It's definitely possible to target a certain surface location on the moon from low Earth orbit and set off on a trajectory to get there with a single burn. However, as the craft(s) approach the moon and enter its sphere of influence, gravity will kick in and increase their relative velocity to the surface. Another burn (suicide burn if you're feeling lucky) would be needed for the soft touchdown.
The moon is also gravitationally very "lumpy", so some small corrections might be needed along the way as well.
First time encountering the phrase “gravitationally lumpy”. I can imagine what that is. But why? I suppose it would naturally occur if the moon were not more or less consistent density. But how would that be possible given the moon’s age and shape. (Roughly spherical I am assuming)
Buried "mascons" (mass concentrations), https://en.wikipedia.org/wiki/Gravitation_of_the_Moon has some nice color maps of the deviations/anomalies. (TLDR: some of it is explained by basalt but not all of it, and it's still being studied, because it interferes with low altitude lunar orbits.)
Space applications of all sorts are screaming out for mass production approaches. With so much design work and verification the actual manufacturing cost tends to be trivial by comparison, the work readily adapted to concurrent manufacturing processes.
When I signed on to a Mars mission in 1999, the scientists told me that’s JPL’s approach: instead of extremely expensive, robust, redundant craft, they would begin to make leaner stuff and worry less when it failed...
Around the same time, Mission Control was replacing their bespoke hardware with COTS and trying to minimize the “glue” HW/SW for space systems.
You'll also see that expertise on a particular instrument package is leveraged over and over across multiple missions.
NASA still has amazing educational outreach and makes incredible software, even for mere mortals.
Combine that with leaving the long-range comms (and higher-powered equipment) in lunar orbit as the "master" for all the probes scattered on the surface, and maybe the problem becomes simpler by breaking it in two.
The challenge, though, isn't just landing softly - it's surviving afterward
Scott Manley put together a great analysis of why it tipped over: https://youtu.be/ISZTTEtHcTg
TL;DW: It had far too much sideways velocity immediately before touchdown, likely due to some guidance-system failure. It would have crashed even if it was crab-shaped instead of tower-shaped.
How can you have temperature without a medium? The lander would have steadily lost temperature through heat radiation, but it's not like the vacuum had a temperature in the crater.
Is there any sort of international body with regulatory power over the moon, or is it completely lawless and unrestricted?
This startup has already crashed two pieces of space junk onto the lunar surface. Can any startup able to get there do whatever they want?
Well, there's a natural barrier to entry, i.e. it costs millions on dollars and years of time to be able to "crash" your "junk" onto the surface. So it's not like a bunch of hobby rocketeers are throwing away their McDonald's garbage.
By the way, in comparison to the cost and complexity of said "junk", everything you own is cluttering up the Earth. You should really do something about that.
Are you making the argument that anyone with enough money should be able to do whatever they want on the moon?
Giant neon McDonalds billboards visible from everywhere on Earth? Mining with zero restriction on impacts to the surface of the Moon or its atmosphere?
Apparently the HN crowd doesn't stand anyone criticizing a "startup", but I'm asking a legitimate question. So far most of the junk we've launched onto the Moon has been in the name of science and operated by nations. An assault by the Free Market is unprecedented. I'm asking a legitimate question about regulation, and implying a question about whether regulation is warranted.
Are you making the argument that for some reason we should heavily discourage lunar exploration for the sake of keeping the moon pristine?
Why is this more important than expanding our ability as a species to explore space?
Regulation doesn't mean "heavily discourage".
Keeping the Moon, or Mars, or Venus as pristine as possible is the only way we can study those environments as they exist in their natural condition. Not to mention that we can't detect the presence of life on those worlds if we've contaminated them with life from our own.
If you think this idea is incompatible with exploration, you can take it up with NASA's Office of Planetary Protection:
> Are you making the argument that anyone with enough money should be able to do whatever they want on the moon?
No, I'm making the argument that anyone who invests the time and money into landing on the moon isn't doing it for giggles and the joy of littering.
And let's be real, if we found "space junk" on the moon of an alien planet, we'd be thrilled as heck, so perhaps we're just seeding the moon with artifacts for alien races.
America wipes it's ass with international regulation.
Besides if countries start shooting eachother in space they'll start doing it on earth.
At what point do you just fire your entire "Land on Moon" software team, and hire a couple young Neil Armstrong wanna-be's, who can hand-land your spacecraft remotely? (In spite of the moon-earth-moon signal lag.)
In this domain, Signal lag seems to be an insurmountable problem, when using remote control. 2.7s delay will be hard to mitigate in a dynamic system.
Unless I am misunderstanding something.
They could hire MMO players from areas with crap ping to the servers :)
You’d probably wanna make sure that’s the problem area first.
Considering the altimeter failed, that seems unlikely to be the case.
Can someone ELI5 why it's at that temperature?
I mean, because it's in the dark I'd expect it to reach equilibrium with space background thermal radiation which is around 3K. Yet its 100K. Where does that heat comes from? It radiates from earth? Conduct through the floor coming from the inner of the moon itself? (Is there some kind of geothermal gradient on the moon BTW?)
There are multiple factors. The biggest ones are reflected sunlight; infrared and thermal conduction from surrounding rocks; and the Moon's internal heat (the region between the core and the mantle has a temperature of over 1,300 C).
Also, little atmosphere means the sun doesn't heat up the area like in your house. Once you're out of the sunlight, it's darn cold.
The question isn't “why is it cold” but the opposite “why is it so hot” (100K when the universe radiation is 3K)
Space is one of those rare fields where partial success actually counts as genuine progress.
Exactly. I look forward to humanity genuinely progressing towards successfully landing stuff on the moon. One day, we may even be able to land humans there! Intuitive systems is really pushing the envelope here, and I think that's worthy of admiration.
This is horribly disappointing but I'm surprised the altimeter failed as I'd have thought this would have been one of the more reliable aspects of the mission.
How does its altimeter work, exactly what tech does it use? It's worth remembering that radar-type altimeters have been around for a long time and are well developed. For example, Little Boy that was dropped on Hiroshima 80 years ago used radar altimeters in a redundancy arrangement (four devices) and that worked on first attempt.
So what went wrong? Second question, was redundancy employed in the altimeter's design? Third, if the altimeter employed redundancy then why weren't its multiple sections of different designs to allow for the possibility that the reflected signal may be weak and noisy?
(The strength of a returned wave from a radar transmission depends on various factors including its wavelength and the properties of the surface it's being reflected from. If there's any doubt the returned signal's S/N would be such that noise could be a problem it'd make sense for a redundant system to employ multiple wavelengths whose frequencies are far enough apart to take advantage of the fact that the moon's surface would reflect different wavelengths in different ways and at different signal strengths.)
> For the second mission in a row, the lander's altimeter failed
That's a bummer. Altimeters are relatively simple and defined hardware as far as I know. Send a ping, receive a ping, calculate. Too bad they didn't incorporate a backup solution.
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the second pic reminded me of the pale blue dot... it's a long way from home...
Why people make temperature in space a big deal? It's mostly vacuum and has no heat capacity. Sun radiation is the real threat, but the concept of temperature can't even be applied to vacuum.
The space surrounding you may not have a temperature but your spacecraft does, and it will lose heat via radiation, batteries and electronics will stop working after your temperature reaches a certain low.
And: if one designed ones spacecraft / lander with a presumption of being exposed to solar radiation, which peaks around 120°C (250°F), then the temperature-management problem is one of excess heat, not insufficient heat, and would feature radiators and foil insulation to avoid acquiring more heat.
Designing for a wide range of temperatures in space where shedding heat is a challenge and running heaters (during dark/cold periods) is necessary, and where at the best of times re-deploying radiators and heat shields is difficult, let alone when the craft is lying on its side.
So ambient temperature matters. As another comment notes, in most cases, the problem is excess heat and the shedding of it. Particularly for Earth-orbiting satellites, which are subject to 1kW/m² solar radiation and are in shadow for only a small portion of their orbit (less with higher altitudes).
Any moderately active satellite has far more issues with excess heat
It depends on the size of the satellite and its power use. Small spacecraft often don't use enough power to generate enough heat to warm themselves. The problem then is batteries get cold (which is one of the places you need heaters) and become inefficient and then you end up in death spiral. Here the probe likely wasn't generating enough power anyway, so that would almost certainly kill it before the cold.
The problem is less the quantity of heat generated than of shedding that heat. Even modest electronics emit several watts of thermal waste heat, and given that the entire satellite is in a highly-insulating vacuum, as well as subject to solar insolation (at 1 kW/m²), it's easy to exceed thermal budgets.
You can do the sums. Spacecraft lose heat by radiation and if you do the sums for a small spacecraft you can see the equilibrium temperature is low enough that you don't need to take any special measures to shed the heat.
The article clearly states that providing enough power to run the heaters was one of the challenges that led to the death of the probe. Satellites are rarely in the shade for an extended period.
It does, but here we are talking about a spacecraft not exposed to sun radiation and without significant amounts of stored energy to generate heat to overcome the heat losses due.
>The space surrounding you may not have a temperature
Just to be pedantic, it actually does, which is the microwave background radiation. But that doesn't detract anything from your point.
There's also ~80,000 molecules per cubic centimeter on the moon. It's extremely thin but there's still stuff out there it's just a VERY slow transfer because there are so few collisions compared to what you'd get on Earth.
Is that really "space" as opposed to "the lingering effects of the big bang"? (or less interestingly, the temperature of the CMB photon gas)
I don't think a photon can exist outside of space, but I'd be very interested to hear of any alternate points of view on that!
What I mean is that isn't the temperature of "space" -- if we're being pedantic. Such a temperature would presumably be measured by the blackbody radiation of... space, if space were a blackbody.
The ground it's laying on though does though.
The problem here isn't the vacuum itself, but that surfaces facing away from the sun radiate heat rapidly into space, causing extremely low temperatures on lander components. That's why temperature still matters practically, even if it's a bit counterintuitive.
Does it matter, if vacuum does not conduct heat? Lander would not experience conductive heat unless it has a great contact with the ground.
It's small enough to lose plenty of heat without conduction.
Because it's lethal
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> The Athena spacecraft was not exactly flying blind as it approached the lunar surface one week ago. The software on board did a credible job of recognizing nearby craters, even with elongated shadows over the terrain. However, the lander's altimeter had failed.
> So while Athena knew where it was relative to the surface of the Moon, the lander did not know how far it was above the surface.
This is really crappy writing. That second paragraph sounds like a self-contradiction. Unless "the lander" is a separate entity from "Athena"? Some publications refuse to use the same term twice, even if it introduces ambiguity as here.
> That second paragraph sounds like a self-contradiction
Aside from the point you made, it actually IS a contradiction. Paraphrased:
>> Athena knew where it was relative to the surface of the Moon, but Athena did not know how far it was above the surface of the moon.
Relative position includes height/altitude? One understands from context, but this sentence does not carry meaning itself.
I read this and I thought it was a bad writing, and I assumed (right or wrong) that (metaphor ensues):
The airplane's pilot could see where the ground was and he estimated it was 1000m-1200m below. But the instrument of the airplane were malfunctioning and reported that the ground was at 500m (or 5000m). This caused the plane to override/resist the pilot's manual landing efforts causing the plane to ultimately crash but not allowing the wheels to come down and the flaps to do turn.
So two different mechanisms, providing contradicting evidence, and the lack of a 'higher' deciding authority to use 'judgment' and/or other inputs to 'decide' which reported measurements are more accurate, and thus make the viable decision/take the viable action.
I get that for such devices every-gram-counts, and perhaps from now on some devices/mechanisms that are truly single-points-of-failure, will get 2x or 3x for redundancy/contingencies. If your ABC-camera fails, it's 'ok' you can still get images from your DEF and GHI will give you some data, reducing to 80% the output of the mission, but still not making it 5%. Your 'landing equipment' fails, and you get out only 5% of the value (flying/trajectory/telemetry of flight/perhaps some eclipse photos).
In their defense, using Athena again here would have definitely sounded strange and not natural. But, they could have used the word “it” without introducing ambiguity, which they do 2 times already.
It knew where it was selenographically, which is what the author means by "relative to the surface of the moon", I think.
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That seems rather uncharitable. I looked through the comments as soon as I saw there wasn't a Celsius figure in the headline or first paragraph.
One conversion comment is on-topic, even though any replies to it are most likely to be off-topic.
I hear you, but it's a classic generic tangent—in fact a classic generic flamewar tangent. HN commenters are asked to resist those - see https://news.ycombinator.com/newsguidelines.html - even though it borders on irresistible.
Edit: but I've put the Celsius number in the title now as well...hopefully that will reduce the swelling.
I noticed it didn't have the Celsius value at the beginning, and a while later I noticed it was there. But "minus 280 F / 173 C" is terrible formatting, it looks like it's positive in Celsius...
Considering the conversion between the 2 temperature scales can flip the sign (e.g. -10C is 14F), "-280F/-173C" would've been a lot clearer.
Ok, I've put minus signs up there.
-280F = -173.33333C
+280F = +137.77777CI refuse to believe anyone knows how cold -280F is.
When you have such extreme temperatures you think in Kelvin or at least Celsius.
Or you can think that way - you at 36 C radiate 900 W away while from our usual environment you get 800+ W radiated (and also transferred by air) at you (with your body producing that 50-100W difference), and at 280F you’d get only mere watts radiated at you from the environment while you still would start radiating at 900 and going quickly downhill from that as you surface quickly cools down (that is supposing you don’t have some performance enhancing stuff Expanse style to generate 900 watts boiling you blood to bring those 900 watts non stop to the skin) until coming into equilibrium with the environment.
It's not like using Kelvin or Celsius helps you grasp these temperatures. -173C is very, very cold, but how cold? What can you compare it to? Not many humans have any experience with something of this scale
Liquid nitrogen (boiling at -196 C) is a semi-common substance that people would have heard of, though not everyone would have seen or interacted with it.
I've seen liquid nitrogen, briefly, as it was sprayed out of a hose. It immediately boiled into a (quite cold) gas, of course. I was told not to play with it too much because they would have to evacuate the building. Oh the joys of "bring your kid to work" days in manufacturing facilities
That's the example Copilot used when asked to make a list of temperatures in 50 C steps with an example or two of something around that temperature that people might have heard of. Also cryogenic freezing of biological samples.
Fair, but in Celsius or Kelvin I know how close it is to absolute zero. In Fahrenheit I have no idea!
Got it, I should use Rankine.
You compare to 0 kelvin, you know where it's on the Celsius scale, not on F
Maybe the Rankine temperature could be provided, as well.
-173C is just twice your typical winter in Yakutia
Anyone who has done cryotherapy?
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Wow. Cosmic resonance man...
I know I'm a snob... but I can't read science news using the imperial system.
You would think either they could parameterise all units or a plausible browser extension could convert elephants to swimmingpools and King's thumbs to badly measured fractions of a diameter.
I made this, but have not tested it yet with this website:
Everyone knows feet and British stones is the way to measure things in space. Just ask any scientician:
Ahhhh...
Speaking of "feet" as a measurement - Randall Carlson has an AMAZING video[0] on the source of the 12 inch foot.
And how its all related to the measurement of the precession of the earth. And yes - its specifically how to measure things in space. And its all from Sacred Geometry.
Well, the definition of 0ºC is based on the freezing point of water at one atmosphere of pressure, which isn't super relevant on the Moon. You could give it in K but that's not very relatable.
-280F, -173C, or 100K is not relatable to anyone except niche researchers. Maybe slap in the extra few people who happen to work with liquid helium and you are still talking about 0% of the population.
I agree, especially scientific articles should just stick to metric, period.
At least inside the article both units are actually used, just the title is imperial only.
But it only looks like Imperial, it's almost certainly actually US Customary.
No sane person can
Minus 173° C. The US does use Fahrenheit, but not for science.
-173°C.
100K
This actually puts it into perspective, knowing it's closer to absolute zero than room temperature.
It’s roughly a third of room temperature.
Which is hard to grok since a third of something warm doesn't seem to be extremely cold.
This is an interesting explanatory challenge.
Temperature is roughly how fast molecules are moving, vibrating etc. And the impact of low/higher temperature are really how fast molecules are knocking you. For an ideal gas, temperature is proportional to the square of the velocity.
So at room temperature (300K), the speed of the molecules is roughly 300^0.5 = 17.3 in some arbitrary units. If you drop down to freezing point of water, (273K), speed is 16.5. And that is starting to get cold. -40C (as cold as most humans will experience) is 15.3. So each drop of 1 in speed is pretty drastic.
At 100K, the speed is 10, or 7 drops from 17. That should be a lot colder than room temperature. But not cold enough. Most of the speed is still there, we haven't even cut it by half. It's the next few 1/3rd cuts of the temperature that will start to get us closer to zero speed.
It's hard, I can imagine the average kinetic energy slowing down, but can't imagine heat halving since there's no halving we can feel without dying.
Humans should experience something within -50°C to 50°C for most, if not their entire lives, but that's just 223K to 323K, maybe that's the range we can understand as a warmth difference, so getting to that temperature might feel like that super wide, in human warmth terms, drop in temperature twice, which still feels unimaginably cold.
It’s sort-of the point to realize that it actually is (a third of something). The lander is receiving a third of the thermal energy that it would receive at room temperature.
Warm-blooded mammals of course have a reference point based on their thermal homeostatic capabilities (ability to maintain body temperature). “Warm” and “cold” is in relation to that.
I don't think that black-body radiative transfer is a linear process.
The Stefan-Boltzman relation says power scales with the fourth power of temperature. So 1/3 absolute temperature would be 1/81 the inbound radiative energy. If you are getting 800W inbound at room temp, you would get 10W inbound at 100K (=300K/3).
Exactly, the Kelvin unit makes it easy to see that. I can't believe they used fucking Fahrenheit in the title.
"You know how hot you feel when you're running a fever? Well, it was nearly three times that cold!"
Ars has been one of the best publications across my whole experience with the internet, going on 20+ years. Without them I wouldn't have been clued into how broken the internet is.
The articles (except for the syndicated Wired articles) are great, but the comment section is Reddit-level degeneracy.
The articles often have good style, but redditor-level insight.
Comment was deleted :(
To be clear, I am in no way a conspiracy theorist, at all. Seriously, not just a bs disclaimer. That said, all of the recent photos of the moon that have come out in the last month or so look, to my eye, super CGI. Just uh, overly smooth and lacking in detail?
Is there a reason for this or am I just tripping?
There is no atmosphere, ergo no light diffusion. Shadows will be crisper, lit spots will be brighter, dark spots darker. It makes sense that such differences could make an image feel "off".
What other pictures are you thinking of? I don’t recall any rovers since china’s (?) last year.
These pictures in particular are taken from a very high altitude, which may explain why they look unnatural?
I’m not sure I get it. Can’t you just look at it yourself? It seems pretty real to me.
> this mission was largely a success. What can he possibly mean by that?
> Compared to the company's first spacecraft, Athena flew smoothly.
Reminds me of the comedian opining on the flipped over airplane.
“Did you know the pilot was a woman? [hecklers] Woah woah, I’m not saying women cant be pilots, thats not even accurate. She flew perfectly….. what I am saying is that she can’t drive”
Crafted by Rajat
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